Crushed Coral Vs. Sand: Which Substrate Is Better?

Perhaps you’re familiar with common corals in aquarium as a marine enthusiast. But is it the only substrate available for your fish tank? Probably not!

A substrate is an integral part of your freshwater aquarium. It adds to the tank’s beauty and promotes good bacteria growth crucial for aquatic life.

However, selecting from various substrates for your home aquarium can be overwhelming, “Crushed corals, sand, stony corals; what to choose?”

We’ll explore common substrates to help you pursue your aquarium passion and make it less stressful and more exciting.

great barrier reef - aquarium benefits of crushed coral

What Is Crushed Coral Substrate?

Crushed coral reef primarily contains a blend of an oyster shell, coral skeleton pieces, and limestone. The substrate was pretty popular among saltwater aquarists decades ago. However, the release of new products on the market replaced it soon.

Generally, crushed coral is an ideal substrate for aquariums with high water flow. – be it saltwater fish tanks or freshwater aquariums. Nonetheless, you must opt for the right grain size.

Finer grain particles, for instance, are not suitable for water with higher flow rates; they create a sandstorm, making water mushy.

Larger grains, however, present an entirely different problem. They are infamous for trapping food leftovers, dirt, and debris.

However, regular maintenance of sand bed helps resolve the issue. On top of that, it prevents the production of harmful compounds, including Nitrates and Ammonia, which feed on the algae needed for aquatic life.

Why Add Crushed Coral to Freshwater Tank?

You might have taken every step to set up your first aquarium tank – from eye-catching plants to quality tank filters. But is that all your fish need to survive?

It is understood that an artificial tank setup cannot beat the ideal water chemistry of natural habitat. Therefore, you need to consider several other factors to help your fish thrive.

For instance, the pH levels of the tank water play a critical role in maintaining aquatic life. Regrettably, food leftovers and fish waste significantly reduce water pH, making it unfit for marine life.

However, adding crushed coral balances the water pH to the needed amount. 

Crushed coral dissolves in water and boosts the pH levels to the optimal amount. Consequently, making a healthy environment for the fish and aquatic plants.

However, note that not all fish require a higher pH level. So if you plan to add it to your tank, make sure you do not exceed the optimal amounts.

Generally, African Cichlid thrives well in harder water. So, if you’re choosing any other species, be cautious with the crushed coral use.

Ways to Add Crushed Coral

There are several methods to add crushed coral substrate to your fish tank. Learning different ways and the ideal amount to add is imperative to reap the benefits of crushed corals.

Via Filter

If you do not want to add crushed coral at the bottom of the tank, you can place it in a filter. Whenever the water pH is out of balance, the crushed coral will dissolve in it, increasing the pH.

However, note that this process works slowly, and you won’t detect optimal pH levels right away. Instead, it can take a few days to a week.

For instance, you can add 1/2 cup of crushed corals per 25 gallons of water. Then, determine your water pH levels after a few days.

If you do not experience any change, consider adding 1/4 cup per 25 gallons every week.

As a Substrate

Aquarium experts suggest keeping the substrate almost 2 inches deep. Adding more can reduce water flow and negatively impact marine life.

You need to calculate the right amount considering your tank’s size. For instance, if you own a 40-gallon tank, 24 cups of crushed coral will do. Likewise, a smaller tank size would require fewer crushed corals.

As a rule of thumb, add 1/2 substrate per gallon. Also, make sure you place the substrate before adding water, plants, and fish to the tank.

Manual Method

Adding crushed coral by hand is downright easier than other methods. However, it is suitable for emergencies only.

Throwing a handful of crushed coral in your aquarium tank can make the water dirty and unappealing.

Therefore, we recommend the first two techniques.

Things to Keep In Mind When Using Crushed Coral

While crushed coral is beneficial to the environment of your fish tank, excess of everything is bad, and the same goes for boosted pH levels.

You need to consider a few things before using them for your aquarium.

  • The marine plants promote algae growth and provide oxygen, making them an integral part of the tank. Adding higher amounts of crushed coral can dramatically alter the water pH, negatively affecting the plants.
  • Crushed corals boost calcium carbonate levels, affecting the hardness and water pH. Therefore, higher calcium carbonate in water indicates less crushed corals needed to alter the pH levels. Make sure you add corals as soon as the carbonate hardness drops to 4. But you must consider your tank size, too.
  • Not all fish require a high pH to thrive. Therefore, avoid adding a significant amount of crushed coral for fish species other than African Cichlid that struggles to survive in lower pH.

What Is Sand Substrate For Your Aquarium?

Sand is infrequently used as a substrate; therefore, not many fish keepers are familiar with it. However, it is pretty useful when added in the right amount. For instance, it doesn’t allow dirt particles to seep through it, unlike gravel.

We’ll discuss two common sand types below.

Live Sand

Live sand features an array of broad-spectrum bacteria. However, the strains are chosen carefully to stimulate the formation of a biological filter in your tank.

Not only does it benefits your tank by allowing for a quicker aquarium cycle, but it also stabilizes the water pH levels.

Dry Sand

As the name implies, dry sand is not wet, unlike live sand. Companies selling aquarium products collect it, dry it, and create packages.

The sands available for a saltwater aquarium primarily consist of aragonite (more on the topic below)

Catfish, goldfish, and plants that feed at the tank bottom survive in the medium to large grain sand.

Is It Right to Blend Crushed Coral With Sand?

Because crushed coral has its pros and sand makes up for a reasonably good substrate, aquarium owners often question whether they can use both for the tank.

If you add sand to the crushed coral, you’ll fill gaps where debris seeps in. This way, you’ll prevent detritus buildup in your tank, reducing the maintenance hassle.

However, make sure you clean out the old substrate lying in your fish tank. Doing otherwise will lock the debris deep within the substrate. Eventually, it’ll release harmful substances or lead to scenarios like, “I have no idea why my fish died.”

To save yourself from unpleasant experiences, add new crushed coral and sand – dry or live.

Investing in a quality sandbed will save you from exposing your fish to ammonia, phosphate, and nitrate.

So, you can mix both substances but do not compromise maintenance.

How About No Substrate?

In the world of corals and sandbeds, people often choose to go substrate-free. This sounds quite unnatural to anyone who owns an aquarium.

Although bare tank bottom looks unappealing, it has a few benefits. For instance, it comes in handy for those who procrastinate on cleaning.

Goldfish, for instance, is quite messy, making cleaning incredibly difficult for owners. Having no substrate at the bottom makes the cleaning process convenient.

For someone who doesn’t mind compromising aquarium aesthetics and prefers a hassle-free cleaning method, adding no substrate can be the right choice.

Which Substrate for a Reef Tank?

Calcite and aragonite are two primary types of substrates available on the market. Check out which one is suitable for your aquarium.

  • Calcite. Calcite is recommended for freshwater aquariums. It is a calcium carbonate mineral that dissolves in water with a relatively low pH and doesn’t mix properly in salt aquariums with a higher pH.
  • Argonite. Argonite, a calcium-based mineral, is ideal for saltwater aquariums and for the right reasons. It dissolves in a solution of pH 8.2, releasing calcium carbonate into the water. This helps marine animals build shells and corals re-build skeletons.

Does Substrate Color Matter?

Substrate color is yet another thing to consider when it comes to setting up your new tank. Because fish are adaptable animals, there isn’t any harm in choosing a color of your choice. However, the benefit of natural gravel is that it is identical to the natural fish habitat.

By the end of the day, it is the maintenance that matters, and you can choose a shade per your preferences.

Crushed Coral Vs. Sand: Which One Is Better?

The choice between crushed coral and sand boils down to your preferences and aquarium setup.

Crushed coral is coarse and traps the biological waste better. Sand, on the other hand, is finer and more convenient to clean.

Nonetheless, the buffering capabilities of both help boost your water pH. Aquarists today consider crushed coral outdated and suggest using sand. However, as long as you understand the requirements of the marine inhabitants and maintain the tank regularly, you can opt for any substrate.

Alternatively, you can place sand at the bottom and cover it with some crushed corals or mix them both.

Aquarium Substrate – Maintenance and Replacement

Aquarium maintenance is crucial to ensure a healthy environment for marine life, and replacing gravel is one of the essential parts of the maintenance.

If you aren’t sure how to change the substrate, follow the tips below.

  • Scoop out the dirt-laden, old substrate and place it in an empty bucket.
  • Use a vacuum to remove underlying debris at the tank bottom
  • Add the new substrate to the aquarium, followed by plants, rocks, and other decors.
  • Carefully move the fish from the holding tank to the main aquarium
  • Because substrate replacement stresses the fish, take steps to alleviate their stress levels. For instance, consider adding a stress coat to the tank and keep the lights off.
  • Feed the fish in small quantities after replacing the substrate. Then, gradually, increase the amount in the coming days.

Note that substrate replacement and tank maintenance isn’t challenging for you only. It can leave the marine animals stressed, and they need time to adapt to the new environment. Make sure you are gentle with the process and keep the tips shared above in mind.

Final Words

If you plan to invest in an aquarium, you must familiarize yourself with the basics. Which substrate you should choose is a key factor to consider.

You can go for crushed coral or sand. The former traps debris better while the latter is easier to clean. Contrarily, you can blend them both to maximize the benefits.